The present invention is an integrated circuit regulator for controlling the current in a variety of MOS circuits. One type of circuit has a cascode transistor with its source electrode coupled to one voltage supply (ground) through a network and its drain electrode connected to an undefined network. Another type of circuit has simply a transistor having its source electrode connected to ground and its drain connected to an undefined network. A third type of circuit which could benefit from the current regulator of the present invention has a transistor with a source electrode connected to a second voltage supply (V.sub.cc) and its drain electrode connected to an undefined network.
Typically with the general cascode transistor-current source MOS circuit there are currents nearly proportional to the square of the supply voltage, V.sub.cc. Power dissipation is thus nearly proportional to the cube of V.sub.cc. Thus, power dissipation can be a significant problem.
Another problem for this general circuit is that the current through the circuit typically varies with processing variations. For example, if processing is "good", the particular lot of integrated circuits has transistors with more current drive. If the processing has not been good, then the current drive of the processed transistor is not as large. Typically with better processing the threshold voltage, V.sub.T, of the MOS transistors in the integrated circuit falls while the .beta.=1/2.mu..sub.O C.sub.OX (W/L) of the individual transistors increases. These processing variations in the transistor device parameters result in operational currents in the general circuit and the integrated circuit containing this circuit to vary wildly depending upon the vagaries of processing.
The present invention solves or substantially mitigates these problems of the general cascode transistor-current source circuit. In one particular embodiment, the current flowing in the circuit is proportional to V.sub.cc, not V.sub.cc.sup.2, and is substantially independent of processing variations.
The present invention also provides current regulation for the other two types of general circuits. Finally the present invention can act as reference voltage generator by providing for a reference voltage equal to the threshold voltage of MOS transistors, V.sub.T.